Discharge device



JUIL A13, ,1944. D. E. MARSHALL E-rm. 2339499 DISCHARGE DEVICE voriginal Filed sept. `26, 1940 INVENTORS D. E MHiE/HLZ hmz cn/06H55ATTORNEY Patented Jan. 18, 1944 DISCHARGE DEVICE Donald E. Marshall,Allwood, and William J.

Knochel, Irvington, N. J., assignors to Westinghouse Electric &Manufacturing Company, East Pittsburgh, Pa., a corporation ofPennsylvania Original application September 26, 1940, Serial No.358,474. Divided and this application April 18, 1942, Serial No. 439,575

v3 claims. (01; 25o-r7.5)

This invention is a division of our prior application directed to ametal-casing discharge device, Serial No. 358,474, filed September 26,1940, which has become Patent No. 2,315,289 entitled Discharge devicewith water cooled baffle, the present invention likewise relating todischarge devices and to such devices utilizing metal casings. A

An object of the present invention is to provide an improved igniter tiplead-in structure.

A further object is to provide a lead-in structure for an igniter tipwhich is rigid and readily fabricated and which introduces noprobabilities of rupture of the insulative portion or of any other partthereof.

A further object of the invention is to prevent mercury or other poolmaterial from sputtering onto the insulative sealing portion of thelead-in structure.

Still further objects will appear both by direct recitation thereof andby implication from the context as the description progresses.

In the accompanying drawing wherein like numerals of reference indicatesimilar parts throughout the several views; K

Figure 1 is a view principally in cross section, of a discharge deviceembodying our invention.

Figure 2 is a cross section on line II-II of Figure 1; and

Figure 3 is a sectional View substantially on the line III-III of Figure2.

In the specic embodiment of the invention illustrated in said drawing,there is shown a tubular inner casing I0, preferably of stainless steel,closed at its lower end by a dish-shaped plate or header I I, also ofstainless or cold-rolled steel, having its downwardly-turned andperipheral flange I2 welded to the said casing Ill. The lower end of thecasing III is flared outward just beyond the lower edge of said flangeI2 and is welded to the said casing where the peripheral surface of theflange and the casing are in peripheral surface Contact. This structurepermits securing an outer casing I3 to the lower flared periphery of theinner casing and provides a space I4 between the casings for passage ofa cooling duid therebetween. The inner casing is closed and evacuatedand has mounted therein toward its upper part an anode I5. A poolcathode I6 is situated upon the header II, and in operation a dischargefrom the said cathode to the said anode is obtained. In order toinstigate le discharge, a starter tip or igniter I'I is employed the tipend of which as shown in Figure 3, dips into the mercury. Said startertip is of high resistance material, preferably boron carbide, which doesnot amalgamate with the mercury. This starter tip requires support andrequires a lead-iny connection and it is those parts which constituteimportant features of the pres- V2li unified therewith. It is pointedout, that the post and lead-in wire areA of appropriately conductive andrelatively inexpensive metal'. The said aligned parts mayboth be ofthesame metal,

lsuch as copper, or if preferred, the post I9 which is within theevacuated casing, may be of steel whereas the lead-in wire 2I which isexposed to the outside atmosphere, may be of different material, such ascopper. The purpose of the inverted cup member 20 is to obtain adequatesupport for the post I9 and also to obtain a vacuumtight seal. Thestructure accordingly contemplates utilization of a nickel-cobalt-ironalloy such as sold under the trade name of Kovar as the material usedfor said cup. The downwardly directed peripheral rim of the cup issealed in the upper edge of a cylinder of borosilicate glass 22. At thelower edge of this glass cylinder is sealed the peripheral upper edge ofthe tubular portion 23 of a anged nipple, the flange 24 whereof is belowthe header II with the adjacent part of the tubular portion of thenipple projecting through a hole in said header. inasmuch as this nippleis likewise a nickelcobalt-iron alloy, or Kovar, the coefficients ofexpansion of said nipple, glass cylinder and cup will be substantiallythe same and there will accordingly be no probability of ruptureoccurring between the parts mentioned. The alloy is strong and will beable to resist deformation and differences in coeicients of expansionthereof and attached material parts. The flange of the nipple isperipherally welded or otherwise secured with a vacuum-tight joint tothe header.

Around the portion of the nipple within the casing and around thesuperposed insulative cylinder, cup and post is a thimble-like metallicshield 25 the closed end of which is above the post and out of contacttherewith. The lower edge of the thimble-like shield is welded orotherwise secured to the -uppersurface of header Il. The shield may beof molybdenum or of coldrolled steel. The shield 25 protects theinsulating material or borosilicate glass 22 during heat treatment andduring operation of the device. Mercury sputtering from the cathode spotinstigated by the igniter tip, cannot coat the glass cylinder andshort-circuit between the cup and nipple in View of the protectionobtained by the shield. A vertical key-slotv 26 provides adequateclearance both for assemblyy purposes and for projection of arm I8therethrough from the interior mounting on the post I9 to the exteriorsupport of igniter tip I'l.

It is apparent that many modifications may be made in the preferredstructurel illustrated and, accordingly, we desire only such limitationsto be imposed upon our invention as are necessitated by the spirit andscope of the following claims.

We claim:

Y l. A discharge device comprising a metal envelope having a bottom, apool cathode in said envelope on the bottom thereof, an anode in saidenvelope spaced above said cathode, means for initiating a discharge,said means being supported from a cup-shaped member the peripheralmargin whereof is directed downwardly toward the bottom of saidenvelope, an insulative cylinder sealed at its upper yedge to the saiddownwardly directed margin of the cup-shaped member and sealed andsupported at its lower edge above the said bottom of the envelope, and ashield around the said insulative cylinder, said shield extendingupwardly from the said bottom of the envelope to a position above thelevel of said insulative cylinder, and said means for initiating thedischarge being outside of and spaced to one side of said shield.

2. A discharge device comprising a metal envelope having a bottom, apool cathode in said envelope on the bottom thereof, an anode in saidenvelope spaced above said cathode, means for initiating a discharge,said means being supported from a cup-shaped member the peripheralmargin whereof is directed downwardly toward the bottom of saidenvelope, an insulative cylinder sealed at its upper edge to the saiddownwardly directed margin of the cup-shaped member and sealed andsupported at its lower edge above the said bottom of the envelope, and ashield around the said insulative cylinder, said shield extendingupwardly from the said bottom of the envelope to a position above thelevel of said insulative cylinder, said shield having a closed top abovethe said insulative cylinder, and said means for initiating thedischarge being outside of and spaced to one side of said shield. 3. Adischarge device comprising a metal envelope having a bottom, a poolcathode in said envelope on the bottom thereof, an anode in saidenvelope spaced above said cathode, means for initiating a discharge,said means being supported from a cup-shaped member the peripheralmargin whereof is directed downwardly toward the bottom of saidenvelope, an insulative cylinder sealed at its upper edge to the saiddownwardly directed margin of the cup-shaped member and sealed andsupported at its lower edge above the said bottom of the envelope, and ashield around the said insulative cylinder, said shield extendingupwardly from the said bottom of the envelope to a position above thelevel of said insulative cylinder, said shield having a slot opening atone side thereof, and an arm projecting through said slot out of contactwith the shield and constituting a support for the discharge initiatingmeans, and a post from the said cup to and supporting said arm.

DONALD E. MARSHALL. WILLIAM J. KNOCHEL.

